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Duchenne Muscular Dystrophy: Genethon presents Two-Year consolidated results of the GNT0004 Gene Therapy

Genethon unveiled the 2-year follow-up data from its GNT0004 gene therapy clinical trial for Duchenne muscular dystrophy, at the American Society of Gene and Cell Therapy, in New Orleans, May 13 – 17, 2025.

Five children aged 6 to 10 years were treated, 2 at the first dose level and 3 at the second dose level (3×10¹³ vg/kg). Safety, efficacy, and pharmacodynamic results show good tolerance of GNT0004, associated with transient immunological prophylactic treatment. Efficacy data reveal microdystrophin expression, a decrease in creatine kinase (CPK) levels, and clinical improvements measured by the NSAA and timed tests.

Patients treated at the effective dose (3×10¹³ vg/kg) showed prolonged improvement or stabilization of motor functions, and significant and persistent reduction in CPK levels, a key marker of muscle damage. 

These data confirm the potential of GNT0004 to durably alter the evolution of the disease. They are particularly convincing as they are accompanied by a comparison with an untreated patient group, matched by age and followed in the same centers by the same practitioners.

At 24 months post-treatment, the key points observed were:

  • Stabilization of motor functions: Treated patients showed prolonged improvement or stabilization of motor functions, measured by the NSAA scale.
  • Significant reduction in CPK levels: An average decrease of over 75% at 18 months, persistent up to 24 months. mois.
  • Confirmed safety: No serious side effects were observed at the selected dose, which is lower than that used in other trials.

Genethon CEO Frederic Revah observed, “The results of our gene therapy GNT0004 are very positive in patients treated at the dose of 3×10¹³ vg/kg, both in terms of microdystrophin expression and clinical efficacy criteria. Besides these results, the advantage of our product lies in the selected dose for the pivotal phase, which is lower than those used in other gene therapy trials for Duchenne Muscular Dystrophy. We are currently preparing the pivotal phase that we will conduct in Europe and the US.”